To measure exhaust gas discharged from the internal combustion engine of the automobile and the like, according to a conventional method, a vehicle mounted on a chassis dynamo apparatus is traveled according to a predetermined travelling mode by an automatic operating robot, discharged exhaust gas is collected by a constant-volume sampling device, and the collected sample gas is supplied to an exhaust gas analyzing apparatus equipped with a plurality of different gas analyzers having different measurement principles, and is measured for each component.
Each of the gas analyzers mounted in the exhaust gas analyzing apparatus includes heating equipment such as a hot hose and a heater, and at measurement, a main body of the gas analyzer and an exhaust gas introduction line are heated to respective analyzable temperatures predetermined according to specifications.
However, it is unsuitable to heat them to the respective predetermined analyzable temperatures during operations other than analysis in terms of costs. For this reason, the conventional apparatuses are configured such that the heating state can be switched among three following phases: (1) an “OFF mode” in which both the gas analyzer main body and the exhaust gas introduction line are not heated, (2) a “pause mode” in which the gas analyzer main body is regulated to have an analyzable temperature of about 191° C., and the exhaust gas introduction line is regulated to have a predetermined intermediate temperature (about 100° C.) that is lower than the analyzable temperature, and (3) a “standby mode” in which both of the gas analyzer main body and the exhaust gas introduction line are regulated to have the analyzable temperature.
However, from the viewpoint of the recent severe energy supply situation and environmental load, it has been demanded to regulate the heating state more finely. Nevertheless, once heating of the gas analyzer main body is stopped and its temperature lowers, even when heating is restarted and the temperature returns to the initial value, it takes time for the analyzer main body to be stably put into an analyzable state without any drift. Specifically, when the heating state is switched from the “OFF mode” to the “standby mode”, it takes at least six hours to regain a stable state.
A plurality of analyzing units and an exhaust gas sampling line, which constitute the exhaust gas analyzing system of the internal combustion engine, each are further equipped with a temperature regulating mechanism formed of a hot hose, a heater, or the like, and at analysis, temperatures of the analyzing units and the exhaust gas sampling line are kept to a specified analyzing temperature (for example, about 191° C.) according to the specifications.
As described above, the specified analyzing temperature is substantially high, and it takes a long time (for example, a few hours in the case of starting at normal temperatures) to stably attain the specified analyzing temperature from a start of the operation of the temperature regulating mechanism.
Some analyzing units such as a hydrogen flame ionization detector and a chemiluminescent NO meter may require dedicated gas (analyzing gas) for analysis of the exhaust gas. For example, to analyze the exhaust gas, the hydrogen flame ionization detector requires hydrogen gas, and the chemiluminescent NO meter requires ozone gas.
In such analyzing units, in addition to temperature stabilization, for example, stabilization of the flow rate of the analyzing gas and purge of inside remaining gas are needed and thus, unless a predetermined time (for example, a few dozen minutes) elapses from a start of the introduction of the analyzing gas, the stable analyzing operation cannot be performed.
Accordingly, to attain the state in which exhaust gas analysis can be immediately started (hereinafter referred to as standby mode), at least, it is necessary to operate the temperature regulating mechanism in advance to attain the specified analyzing temperature, and start the introduction of the analyzing gas to keep the analyzing units in the stably-operable state.
Thus, conventionally, the operations of the temperature regulating mechanism and the introduction of the analyzing gas are simultaneously started and then, proceed in parallel, thereby reducing the time required to attain the standby mode.
For example, JPA 2002-71524 describes a scheduler for automatically setting operation timings of the exhaust gas analyzing apparatus and the dynamo, which are used in an automobile test, to efficiently spend time for the test. When receiving a command of standby mode from the scheduler, the exhaust gas analyzing apparatus starts the operation of the temperature regulating mechanism and the introduction of the analyzing gas at the same time.
However, since a temperature stabilizing time taken by the temperature regulating mechanism is generally longer than a time that elapses before the analyzing units become stably operable from the start of the introduction of the analyzing gas, during a time elapses before the temperature becomes stable after the analyzing units become stably operable, the analyzing units are in a waiting state in despite of the introduction of the analyzing gas, uselessly consuming the analyzing gas.